The field of the invention is prison apparatus and the invention relates more particularly to view ports or observation panels useful in prisons, mental institutions and other locations requiring a high degree of security.
View ports have been used in prison doors since the early days of prison construction. Such view ports were typically a solid plate which could be opened or closed from outside of the door of the cell. The plate was either hinged or provided with means for sliding and was locked or latched from outside of the cell. More recently, a lens member was added but basically view ports are still typically installed in cell doors and operated from the front surface of the door. In many prisons, the cell door is not readily accessible without passing through a guard station outside of a corridor which leads to a group of cells. Thus, in order to view the interior of a cell, it was necessary to pass through an additional guard station. Prisons invariably have a pipe chase which is a corridor located along a wall of the cell which is most commonly the opposite wall from the prison door. This pipe chase is often accessible without the necessity of passing through the additional guard station required to reach the cell door. Because of the wall thickness and the perceived difficulty and expense of installing a view port in a wall, installation in the wall between the cell and the pipe chase had been considered impractical.